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Boiler make and models

Long winded question here. I'm moving my boiler with indirect domestic hot water tank to new location in my home because the huge flue runs thru the master bedroom closet and she wants it moved. I want a boiler that the flue can exit a side wall and the flue does not need to run above the roof line. Our current system consists of 700 sq. feet of in-floor heat and about 1000 sq. feet of rooms with oversized aluminum wall hung radiators. Everything including domestic hot water uses 125 degree water and works very well. I don't want to heat the water hotter than this just to cool it down again so I need a boiler that I can set at 125 degrees. I want a boiler that modulates but I don't believe a condensing boiler will work because of the low temperature I require. I am considering a closed loop system for heat only but not sure what to use for domestic hot water supply. I am also considering using the current indirect water tank but with newer small flu boiler that will exit side wall as I mentioned earlier. Any suggestions as to makes and models with these specs built in? Thanks

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Comments

work better and more efficiently at low temperatures. If you can heat the place using 125ºF water on the coldest day of the year, you will see fantastic performance out of one. Most if not all of them will work with sidewall venting.

You want to start the process with a heat loss calculation. Getting the right size boiler is very important.

You have been misinformed about condensing boilers. They love low temps,in fact, the lower the temp, the more efficient they are. They will automatically adjust the temp based on the outdoor temp to give max comfort and efficiency.

Using your existing indirect is not an issue.

Sidewall venting is not an issue.

You will need a drain,or a pump to a drain for the condensate.

I would look at a boiler with a "firetube" heat exchanger like triangle tube or lochinvar.

Your boiler size will be less than 60,000 BTU. If you have contractors recommending larger boilers, it should be a red flag.

I did my own heat loss calculations. My schooling was in solar so know a little bit about heat loss. The wood floors we installed only allow 125 degree heat under the installation so that is the temperature we use. knowing that, we oversized all wall hung radiators for the lower temperature and this works really well also. I am weary about condensing boilers. I know people that have had problems with these. Guess i'm kinda old school and want a less complicated boiler system that I can understand. Thanks for your input.

Our current boiler has an output of 96K btu. I like the boiler but not the huge 12 inch flue. Also there are two huge air intake tubes that bring in outside air to the garage where this is located. In the future I want to also heat the garage and want to eliminate all this cold air. Thanks

I didn't expect such a quick response to my questions. I've heard installers oversize boilers and furnaces. Guess it's better to be safe than sorry. I thought condensing boilers needed to condense--thus hotter temp settings were used then cold water was introduced to cause condensing. Is this old school or was I misinformed?

Boiler was not designed for this temp. It's an 1998 Crown boiler but plumber adjusted it to lowest setting to provide this temp. Have temperature gauges attached everywhere inline to show temp output. Even the plumber didn't think it would work properly but this has been working for three years now without problems.

Your existing boiler should not be set that low. It causes the acidic condensation to rain down the flue and into the boiler. This damages the boiler and the flue. This is a big concern if the flue runs through a bedroom closet. CO poisoning is a scary thing.

Condensing boilers are designed to run at low temps.

Many boilers are oversized. This decreases efficiency and longevity and increases maintenance.A heat loss calc is mandatory.

I was wondering about the temp setting on this boiler also. Guess it's a good idea to get it replaced with a correct functioning boiler soon. I'm surprised it has worked this well for so long. We really cant understand why they put this boiler in the garage when they built a furnace room just for one. I'll read the information you have sent. Thanks

will be determined by your heat loss on a design (coldest) day. Many small houses and most newer mid-size houses require less than the smallest currently available boilers can put out. At that point, the minimum output of the boiler becomes more important than its maximum output. If you have an Android or IOS device, http://www.slantfin.com/index.php/homeowners/ipadapp will make the heat loss calc relatively painless.

Upon reading further on the subject of condensing boilers I have found that the return temperature of heated water after it has run thru radiators and in-floor heating should be 135 degrees or so. This is even warmer than I currently run thru my system before running thru the rads and in-floor heat. I don't like the idea of super heating water just to cool it down again. If I can only run 125 degree water thru the system to begin with, I see a problem here.

I know this boiler is running at a super low tem. Output is only 125 degrees. Like I said, I oversized my wall hung rads and only require 125 degree temps to keep everything toasty. Even our 700 sq. ft of in-floor heat that has 3/8 inch pex running thru it is keeping us warm. I want to find a way to keep this temp input of 125 degrees without destroying a boiler in the process. My questoin is (and I know everyone hates water heaters--even Polaris) is weather I should consider a hot water heat system? I could just run one at 125 degrees and not worry about poisoning us here or destroying a boiler.

would I have to run higher temp water to the rads or the in-floor heat.

It may be that you have to run a higher temp water in the rads than the in-floor heat. And that would have nothing to do with whether your boiler is condensing or not.

To get the best results from a condensing boiler, you will want to have as low a return water temperature as possible. I sometimes get return termperatures of about 75F from my in-floor heating zone, but almost 110F from my baseboard zone.

To get the best results from a non-condensing boiler, you will need a much higher return water temperature to prevent destroying the boiler. I am not an expert, but I gather you will need to have return temperatures of the order of 140F, although I have read that a few can go down a little lower. Rely on the experts here for the correct number.

If, in fact you are getting enough heat with the low temperatures you report, then if it were not for the cost of replacing a working non-condensing boiler with a condensing one (with outdoor reset), you would be justified to replace the existing boiler right away, since operating the non condensing boiler at the temperatures you report is going to destroy it in short order anyway. I suppose the vent pipe will be the first to go, then the boiler castings.

If you cannot replace the existing boiler, you will want to get some temperature mixing valves and stuff so that the minimum temperature returned to your boiler is over 140F, and that the temperatures delivered to your heating zones, especially the in-floor zone are as low as you are using now.. Fixed temperature mixing valves should be able to regulate the temperatures supplied to the radiators and the in-floor zones. Protection of the boiler is a little more complicated, but it can be done. Whether the cost of all these valves (some of them are pretty clever), is worth it or not I cannot say. At some point going to a mod-con boiler may even be cheaper, especially in the realm of comfort and fuel cost.

Since your system has enough heat emitters to heat the building at such low supply and return temperatures, it seems to be an ideal setup for a mod-con boiler. The only question I would have is if you can get a small enough mod-con boiler; i.e., one that will modulate low enough on warm days.